[AMDGPU][AsmParser][NFC] Get rid of custom default operand handlers.
[llvm-project.git] / clang / lib / CodeGen / CGCleanup.cpp
blob0bbab283603d986f5623be4531a2e6149f291d9a
1 //===--- CGCleanup.cpp - Bookkeeping and code emission for cleanups -------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 // This file contains code dealing with the IR generation for cleanups
10 // and related information.
12 // A "cleanup" is a piece of code which needs to be executed whenever
13 // control transfers out of a particular scope. This can be
14 // conditionalized to occur only on exceptional control flow, only on
15 // normal control flow, or both.
17 //===----------------------------------------------------------------------===//
19 #include "CGCleanup.h"
20 #include "CodeGenFunction.h"
21 #include "llvm/Support/SaveAndRestore.h"
23 using namespace clang;
24 using namespace CodeGen;
26 bool DominatingValue<RValue>::saved_type::needsSaving(RValue rv) {
27 if (rv.isScalar())
28 return DominatingLLVMValue::needsSaving(rv.getScalarVal());
29 if (rv.isAggregate())
30 return DominatingLLVMValue::needsSaving(rv.getAggregatePointer());
31 return true;
34 DominatingValue<RValue>::saved_type
35 DominatingValue<RValue>::saved_type::save(CodeGenFunction &CGF, RValue rv) {
36 if (rv.isScalar()) {
37 llvm::Value *V = rv.getScalarVal();
39 // These automatically dominate and don't need to be saved.
40 if (!DominatingLLVMValue::needsSaving(V))
41 return saved_type(V, nullptr, ScalarLiteral);
43 // Everything else needs an alloca.
44 Address addr =
45 CGF.CreateDefaultAlignTempAlloca(V->getType(), "saved-rvalue");
46 CGF.Builder.CreateStore(V, addr);
47 return saved_type(addr.getPointer(), nullptr, ScalarAddress);
50 if (rv.isComplex()) {
51 CodeGenFunction::ComplexPairTy V = rv.getComplexVal();
52 llvm::Type *ComplexTy =
53 llvm::StructType::get(V.first->getType(), V.second->getType());
54 Address addr = CGF.CreateDefaultAlignTempAlloca(ComplexTy, "saved-complex");
55 CGF.Builder.CreateStore(V.first, CGF.Builder.CreateStructGEP(addr, 0));
56 CGF.Builder.CreateStore(V.second, CGF.Builder.CreateStructGEP(addr, 1));
57 return saved_type(addr.getPointer(), nullptr, ComplexAddress);
60 assert(rv.isAggregate());
61 Address V = rv.getAggregateAddress(); // TODO: volatile?
62 if (!DominatingLLVMValue::needsSaving(V.getPointer()))
63 return saved_type(V.getPointer(), V.getElementType(), AggregateLiteral,
64 V.getAlignment().getQuantity());
66 Address addr =
67 CGF.CreateTempAlloca(V.getType(), CGF.getPointerAlign(), "saved-rvalue");
68 CGF.Builder.CreateStore(V.getPointer(), addr);
69 return saved_type(addr.getPointer(), V.getElementType(), AggregateAddress,
70 V.getAlignment().getQuantity());
73 /// Given a saved r-value produced by SaveRValue, perform the code
74 /// necessary to restore it to usability at the current insertion
75 /// point.
76 RValue DominatingValue<RValue>::saved_type::restore(CodeGenFunction &CGF) {
77 auto getSavingAddress = [&](llvm::Value *value) {
78 auto *AI = cast<llvm::AllocaInst>(value);
79 return Address(value, AI->getAllocatedType(),
80 CharUnits::fromQuantity(AI->getAlign().value()));
82 switch (K) {
83 case ScalarLiteral:
84 return RValue::get(Value);
85 case ScalarAddress:
86 return RValue::get(CGF.Builder.CreateLoad(getSavingAddress(Value)));
87 case AggregateLiteral:
88 return RValue::getAggregate(
89 Address(Value, ElementType, CharUnits::fromQuantity(Align)));
90 case AggregateAddress: {
91 auto addr = CGF.Builder.CreateLoad(getSavingAddress(Value));
92 return RValue::getAggregate(
93 Address(addr, ElementType, CharUnits::fromQuantity(Align)));
95 case ComplexAddress: {
96 Address address = getSavingAddress(Value);
97 llvm::Value *real =
98 CGF.Builder.CreateLoad(CGF.Builder.CreateStructGEP(address, 0));
99 llvm::Value *imag =
100 CGF.Builder.CreateLoad(CGF.Builder.CreateStructGEP(address, 1));
101 return RValue::getComplex(real, imag);
105 llvm_unreachable("bad saved r-value kind");
108 /// Push an entry of the given size onto this protected-scope stack.
109 char *EHScopeStack::allocate(size_t Size) {
110 Size = llvm::alignTo(Size, ScopeStackAlignment);
111 if (!StartOfBuffer) {
112 unsigned Capacity = 1024;
113 while (Capacity < Size) Capacity *= 2;
114 StartOfBuffer = new char[Capacity];
115 StartOfData = EndOfBuffer = StartOfBuffer + Capacity;
116 } else if (static_cast<size_t>(StartOfData - StartOfBuffer) < Size) {
117 unsigned CurrentCapacity = EndOfBuffer - StartOfBuffer;
118 unsigned UsedCapacity = CurrentCapacity - (StartOfData - StartOfBuffer);
120 unsigned NewCapacity = CurrentCapacity;
121 do {
122 NewCapacity *= 2;
123 } while (NewCapacity < UsedCapacity + Size);
125 char *NewStartOfBuffer = new char[NewCapacity];
126 char *NewEndOfBuffer = NewStartOfBuffer + NewCapacity;
127 char *NewStartOfData = NewEndOfBuffer - UsedCapacity;
128 memcpy(NewStartOfData, StartOfData, UsedCapacity);
129 delete [] StartOfBuffer;
130 StartOfBuffer = NewStartOfBuffer;
131 EndOfBuffer = NewEndOfBuffer;
132 StartOfData = NewStartOfData;
135 assert(StartOfBuffer + Size <= StartOfData);
136 StartOfData -= Size;
137 return StartOfData;
140 void EHScopeStack::deallocate(size_t Size) {
141 StartOfData += llvm::alignTo(Size, ScopeStackAlignment);
144 bool EHScopeStack::containsOnlyLifetimeMarkers(
145 EHScopeStack::stable_iterator Old) const {
146 for (EHScopeStack::iterator it = begin(); stabilize(it) != Old; it++) {
147 EHCleanupScope *cleanup = dyn_cast<EHCleanupScope>(&*it);
148 if (!cleanup || !cleanup->isLifetimeMarker())
149 return false;
152 return true;
155 bool EHScopeStack::requiresLandingPad() const {
156 for (stable_iterator si = getInnermostEHScope(); si != stable_end(); ) {
157 // Skip lifetime markers.
158 if (auto *cleanup = dyn_cast<EHCleanupScope>(&*find(si)))
159 if (cleanup->isLifetimeMarker()) {
160 si = cleanup->getEnclosingEHScope();
161 continue;
163 return true;
166 return false;
169 EHScopeStack::stable_iterator
170 EHScopeStack::getInnermostActiveNormalCleanup() const {
171 for (stable_iterator si = getInnermostNormalCleanup(), se = stable_end();
172 si != se; ) {
173 EHCleanupScope &cleanup = cast<EHCleanupScope>(*find(si));
174 if (cleanup.isActive()) return si;
175 si = cleanup.getEnclosingNormalCleanup();
177 return stable_end();
181 void *EHScopeStack::pushCleanup(CleanupKind Kind, size_t Size) {
182 char *Buffer = allocate(EHCleanupScope::getSizeForCleanupSize(Size));
183 bool IsNormalCleanup = Kind & NormalCleanup;
184 bool IsEHCleanup = Kind & EHCleanup;
185 bool IsLifetimeMarker = Kind & LifetimeMarker;
187 // Per C++ [except.terminate], it is implementation-defined whether none,
188 // some, or all cleanups are called before std::terminate. Thus, when
189 // terminate is the current EH scope, we may skip adding any EH cleanup
190 // scopes.
191 if (InnermostEHScope != stable_end() &&
192 find(InnermostEHScope)->getKind() == EHScope::Terminate)
193 IsEHCleanup = false;
195 EHCleanupScope *Scope =
196 new (Buffer) EHCleanupScope(IsNormalCleanup,
197 IsEHCleanup,
198 Size,
199 BranchFixups.size(),
200 InnermostNormalCleanup,
201 InnermostEHScope);
202 if (IsNormalCleanup)
203 InnermostNormalCleanup = stable_begin();
204 if (IsEHCleanup)
205 InnermostEHScope = stable_begin();
206 if (IsLifetimeMarker)
207 Scope->setLifetimeMarker();
209 // With Windows -EHa, Invoke llvm.seh.scope.begin() for EHCleanup
210 if (CGF->getLangOpts().EHAsynch && IsEHCleanup && !IsLifetimeMarker &&
211 CGF->getTarget().getCXXABI().isMicrosoft())
212 CGF->EmitSehCppScopeBegin();
214 return Scope->getCleanupBuffer();
217 void EHScopeStack::popCleanup() {
218 assert(!empty() && "popping exception stack when not empty");
220 assert(isa<EHCleanupScope>(*begin()));
221 EHCleanupScope &Cleanup = cast<EHCleanupScope>(*begin());
222 InnermostNormalCleanup = Cleanup.getEnclosingNormalCleanup();
223 InnermostEHScope = Cleanup.getEnclosingEHScope();
224 deallocate(Cleanup.getAllocatedSize());
226 // Destroy the cleanup.
227 Cleanup.Destroy();
229 // Check whether we can shrink the branch-fixups stack.
230 if (!BranchFixups.empty()) {
231 // If we no longer have any normal cleanups, all the fixups are
232 // complete.
233 if (!hasNormalCleanups())
234 BranchFixups.clear();
236 // Otherwise we can still trim out unnecessary nulls.
237 else
238 popNullFixups();
242 EHFilterScope *EHScopeStack::pushFilter(unsigned numFilters) {
243 assert(getInnermostEHScope() == stable_end());
244 char *buffer = allocate(EHFilterScope::getSizeForNumFilters(numFilters));
245 EHFilterScope *filter = new (buffer) EHFilterScope(numFilters);
246 InnermostEHScope = stable_begin();
247 return filter;
250 void EHScopeStack::popFilter() {
251 assert(!empty() && "popping exception stack when not empty");
253 EHFilterScope &filter = cast<EHFilterScope>(*begin());
254 deallocate(EHFilterScope::getSizeForNumFilters(filter.getNumFilters()));
256 InnermostEHScope = filter.getEnclosingEHScope();
259 EHCatchScope *EHScopeStack::pushCatch(unsigned numHandlers) {
260 char *buffer = allocate(EHCatchScope::getSizeForNumHandlers(numHandlers));
261 EHCatchScope *scope =
262 new (buffer) EHCatchScope(numHandlers, InnermostEHScope);
263 InnermostEHScope = stable_begin();
264 return scope;
267 void EHScopeStack::pushTerminate() {
268 char *Buffer = allocate(EHTerminateScope::getSize());
269 new (Buffer) EHTerminateScope(InnermostEHScope);
270 InnermostEHScope = stable_begin();
273 /// Remove any 'null' fixups on the stack. However, we can't pop more
274 /// fixups than the fixup depth on the innermost normal cleanup, or
275 /// else fixups that we try to add to that cleanup will end up in the
276 /// wrong place. We *could* try to shrink fixup depths, but that's
277 /// actually a lot of work for little benefit.
278 void EHScopeStack::popNullFixups() {
279 // We expect this to only be called when there's still an innermost
280 // normal cleanup; otherwise there really shouldn't be any fixups.
281 assert(hasNormalCleanups());
283 EHScopeStack::iterator it = find(InnermostNormalCleanup);
284 unsigned MinSize = cast<EHCleanupScope>(*it).getFixupDepth();
285 assert(BranchFixups.size() >= MinSize && "fixup stack out of order");
287 while (BranchFixups.size() > MinSize &&
288 BranchFixups.back().Destination == nullptr)
289 BranchFixups.pop_back();
292 Address CodeGenFunction::createCleanupActiveFlag() {
293 // Create a variable to decide whether the cleanup needs to be run.
294 Address active = CreateTempAllocaWithoutCast(
295 Builder.getInt1Ty(), CharUnits::One(), "cleanup.cond");
297 // Initialize it to false at a site that's guaranteed to be run
298 // before each evaluation.
299 setBeforeOutermostConditional(Builder.getFalse(), active);
301 // Initialize it to true at the current location.
302 Builder.CreateStore(Builder.getTrue(), active);
304 return active;
307 void CodeGenFunction::initFullExprCleanupWithFlag(Address ActiveFlag) {
308 // Set that as the active flag in the cleanup.
309 EHCleanupScope &cleanup = cast<EHCleanupScope>(*EHStack.begin());
310 assert(!cleanup.hasActiveFlag() && "cleanup already has active flag?");
311 cleanup.setActiveFlag(ActiveFlag);
313 if (cleanup.isNormalCleanup()) cleanup.setTestFlagInNormalCleanup();
314 if (cleanup.isEHCleanup()) cleanup.setTestFlagInEHCleanup();
317 void EHScopeStack::Cleanup::anchor() {}
319 static void createStoreInstBefore(llvm::Value *value, Address addr,
320 llvm::Instruction *beforeInst) {
321 auto store = new llvm::StoreInst(value, addr.getPointer(), beforeInst);
322 store->setAlignment(addr.getAlignment().getAsAlign());
325 static llvm::LoadInst *createLoadInstBefore(Address addr, const Twine &name,
326 llvm::Instruction *beforeInst) {
327 return new llvm::LoadInst(addr.getElementType(), addr.getPointer(), name,
328 false, addr.getAlignment().getAsAlign(),
329 beforeInst);
332 /// All the branch fixups on the EH stack have propagated out past the
333 /// outermost normal cleanup; resolve them all by adding cases to the
334 /// given switch instruction.
335 static void ResolveAllBranchFixups(CodeGenFunction &CGF,
336 llvm::SwitchInst *Switch,
337 llvm::BasicBlock *CleanupEntry) {
338 llvm::SmallPtrSet<llvm::BasicBlock*, 4> CasesAdded;
340 for (unsigned I = 0, E = CGF.EHStack.getNumBranchFixups(); I != E; ++I) {
341 // Skip this fixup if its destination isn't set.
342 BranchFixup &Fixup = CGF.EHStack.getBranchFixup(I);
343 if (Fixup.Destination == nullptr) continue;
345 // If there isn't an OptimisticBranchBlock, then InitialBranch is
346 // still pointing directly to its destination; forward it to the
347 // appropriate cleanup entry. This is required in the specific
348 // case of
349 // { std::string s; goto lbl; }
350 // lbl:
351 // i.e. where there's an unresolved fixup inside a single cleanup
352 // entry which we're currently popping.
353 if (Fixup.OptimisticBranchBlock == nullptr) {
354 createStoreInstBefore(CGF.Builder.getInt32(Fixup.DestinationIndex),
355 CGF.getNormalCleanupDestSlot(),
356 Fixup.InitialBranch);
357 Fixup.InitialBranch->setSuccessor(0, CleanupEntry);
360 // Don't add this case to the switch statement twice.
361 if (!CasesAdded.insert(Fixup.Destination).second)
362 continue;
364 Switch->addCase(CGF.Builder.getInt32(Fixup.DestinationIndex),
365 Fixup.Destination);
368 CGF.EHStack.clearFixups();
371 /// Transitions the terminator of the given exit-block of a cleanup to
372 /// be a cleanup switch.
373 static llvm::SwitchInst *TransitionToCleanupSwitch(CodeGenFunction &CGF,
374 llvm::BasicBlock *Block) {
375 // If it's a branch, turn it into a switch whose default
376 // destination is its original target.
377 llvm::Instruction *Term = Block->getTerminator();
378 assert(Term && "can't transition block without terminator");
380 if (llvm::BranchInst *Br = dyn_cast<llvm::BranchInst>(Term)) {
381 assert(Br->isUnconditional());
382 auto Load = createLoadInstBefore(CGF.getNormalCleanupDestSlot(),
383 "cleanup.dest", Term);
384 llvm::SwitchInst *Switch =
385 llvm::SwitchInst::Create(Load, Br->getSuccessor(0), 4, Block);
386 Br->eraseFromParent();
387 return Switch;
388 } else {
389 return cast<llvm::SwitchInst>(Term);
393 void CodeGenFunction::ResolveBranchFixups(llvm::BasicBlock *Block) {
394 assert(Block && "resolving a null target block");
395 if (!EHStack.getNumBranchFixups()) return;
397 assert(EHStack.hasNormalCleanups() &&
398 "branch fixups exist with no normal cleanups on stack");
400 llvm::SmallPtrSet<llvm::BasicBlock*, 4> ModifiedOptimisticBlocks;
401 bool ResolvedAny = false;
403 for (unsigned I = 0, E = EHStack.getNumBranchFixups(); I != E; ++I) {
404 // Skip this fixup if its destination doesn't match.
405 BranchFixup &Fixup = EHStack.getBranchFixup(I);
406 if (Fixup.Destination != Block) continue;
408 Fixup.Destination = nullptr;
409 ResolvedAny = true;
411 // If it doesn't have an optimistic branch block, LatestBranch is
412 // already pointing to the right place.
413 llvm::BasicBlock *BranchBB = Fixup.OptimisticBranchBlock;
414 if (!BranchBB)
415 continue;
417 // Don't process the same optimistic branch block twice.
418 if (!ModifiedOptimisticBlocks.insert(BranchBB).second)
419 continue;
421 llvm::SwitchInst *Switch = TransitionToCleanupSwitch(*this, BranchBB);
423 // Add a case to the switch.
424 Switch->addCase(Builder.getInt32(Fixup.DestinationIndex), Block);
427 if (ResolvedAny)
428 EHStack.popNullFixups();
431 /// Pops cleanup blocks until the given savepoint is reached.
432 void CodeGenFunction::PopCleanupBlocks(
433 EHScopeStack::stable_iterator Old,
434 std::initializer_list<llvm::Value **> ValuesToReload) {
435 assert(Old.isValid());
437 bool HadBranches = false;
438 while (EHStack.stable_begin() != Old) {
439 EHCleanupScope &Scope = cast<EHCleanupScope>(*EHStack.begin());
440 HadBranches |= Scope.hasBranches();
442 // As long as Old strictly encloses the scope's enclosing normal
443 // cleanup, we're going to emit another normal cleanup which
444 // fallthrough can propagate through.
445 bool FallThroughIsBranchThrough =
446 Old.strictlyEncloses(Scope.getEnclosingNormalCleanup());
448 PopCleanupBlock(FallThroughIsBranchThrough);
451 // If we didn't have any branches, the insertion point before cleanups must
452 // dominate the current insertion point and we don't need to reload any
453 // values.
454 if (!HadBranches)
455 return;
457 // Spill and reload all values that the caller wants to be live at the current
458 // insertion point.
459 for (llvm::Value **ReloadedValue : ValuesToReload) {
460 auto *Inst = dyn_cast_or_null<llvm::Instruction>(*ReloadedValue);
461 if (!Inst)
462 continue;
464 // Don't spill static allocas, they dominate all cleanups. These are created
465 // by binding a reference to a local variable or temporary.
466 auto *AI = dyn_cast<llvm::AllocaInst>(Inst);
467 if (AI && AI->isStaticAlloca())
468 continue;
470 Address Tmp =
471 CreateDefaultAlignTempAlloca(Inst->getType(), "tmp.exprcleanup");
473 // Find an insertion point after Inst and spill it to the temporary.
474 llvm::BasicBlock::iterator InsertBefore;
475 if (auto *Invoke = dyn_cast<llvm::InvokeInst>(Inst))
476 InsertBefore = Invoke->getNormalDest()->getFirstInsertionPt();
477 else
478 InsertBefore = std::next(Inst->getIterator());
479 CGBuilderTy(CGM, &*InsertBefore).CreateStore(Inst, Tmp);
481 // Reload the value at the current insertion point.
482 *ReloadedValue = Builder.CreateLoad(Tmp);
486 /// Pops cleanup blocks until the given savepoint is reached, then add the
487 /// cleanups from the given savepoint in the lifetime-extended cleanups stack.
488 void CodeGenFunction::PopCleanupBlocks(
489 EHScopeStack::stable_iterator Old, size_t OldLifetimeExtendedSize,
490 std::initializer_list<llvm::Value **> ValuesToReload) {
491 PopCleanupBlocks(Old, ValuesToReload);
493 // Move our deferred cleanups onto the EH stack.
494 for (size_t I = OldLifetimeExtendedSize,
495 E = LifetimeExtendedCleanupStack.size(); I != E; /**/) {
496 // Alignment should be guaranteed by the vptrs in the individual cleanups.
497 assert((I % alignof(LifetimeExtendedCleanupHeader) == 0) &&
498 "misaligned cleanup stack entry");
500 LifetimeExtendedCleanupHeader &Header =
501 reinterpret_cast<LifetimeExtendedCleanupHeader&>(
502 LifetimeExtendedCleanupStack[I]);
503 I += sizeof(Header);
505 EHStack.pushCopyOfCleanup(Header.getKind(),
506 &LifetimeExtendedCleanupStack[I],
507 Header.getSize());
508 I += Header.getSize();
510 if (Header.isConditional()) {
511 Address ActiveFlag =
512 reinterpret_cast<Address &>(LifetimeExtendedCleanupStack[I]);
513 initFullExprCleanupWithFlag(ActiveFlag);
514 I += sizeof(ActiveFlag);
517 LifetimeExtendedCleanupStack.resize(OldLifetimeExtendedSize);
520 static llvm::BasicBlock *CreateNormalEntry(CodeGenFunction &CGF,
521 EHCleanupScope &Scope) {
522 assert(Scope.isNormalCleanup());
523 llvm::BasicBlock *Entry = Scope.getNormalBlock();
524 if (!Entry) {
525 Entry = CGF.createBasicBlock("cleanup");
526 Scope.setNormalBlock(Entry);
528 return Entry;
531 /// Attempts to reduce a cleanup's entry block to a fallthrough. This
532 /// is basically llvm::MergeBlockIntoPredecessor, except
533 /// simplified/optimized for the tighter constraints on cleanup blocks.
535 /// Returns the new block, whatever it is.
536 static llvm::BasicBlock *SimplifyCleanupEntry(CodeGenFunction &CGF,
537 llvm::BasicBlock *Entry) {
538 llvm::BasicBlock *Pred = Entry->getSinglePredecessor();
539 if (!Pred) return Entry;
541 llvm::BranchInst *Br = dyn_cast<llvm::BranchInst>(Pred->getTerminator());
542 if (!Br || Br->isConditional()) return Entry;
543 assert(Br->getSuccessor(0) == Entry);
545 // If we were previously inserting at the end of the cleanup entry
546 // block, we'll need to continue inserting at the end of the
547 // predecessor.
548 bool WasInsertBlock = CGF.Builder.GetInsertBlock() == Entry;
549 assert(!WasInsertBlock || CGF.Builder.GetInsertPoint() == Entry->end());
551 // Kill the branch.
552 Br->eraseFromParent();
554 // Replace all uses of the entry with the predecessor, in case there
555 // are phis in the cleanup.
556 Entry->replaceAllUsesWith(Pred);
558 // Merge the blocks.
559 Pred->splice(Pred->end(), Entry);
561 // Kill the entry block.
562 Entry->eraseFromParent();
564 if (WasInsertBlock)
565 CGF.Builder.SetInsertPoint(Pred);
567 return Pred;
570 static void EmitCleanup(CodeGenFunction &CGF,
571 EHScopeStack::Cleanup *Fn,
572 EHScopeStack::Cleanup::Flags flags,
573 Address ActiveFlag) {
574 // If there's an active flag, load it and skip the cleanup if it's
575 // false.
576 llvm::BasicBlock *ContBB = nullptr;
577 if (ActiveFlag.isValid()) {
578 ContBB = CGF.createBasicBlock("cleanup.done");
579 llvm::BasicBlock *CleanupBB = CGF.createBasicBlock("cleanup.action");
580 llvm::Value *IsActive
581 = CGF.Builder.CreateLoad(ActiveFlag, "cleanup.is_active");
582 CGF.Builder.CreateCondBr(IsActive, CleanupBB, ContBB);
583 CGF.EmitBlock(CleanupBB);
586 // Ask the cleanup to emit itself.
587 Fn->Emit(CGF, flags);
588 assert(CGF.HaveInsertPoint() && "cleanup ended with no insertion point?");
590 // Emit the continuation block if there was an active flag.
591 if (ActiveFlag.isValid())
592 CGF.EmitBlock(ContBB);
595 static void ForwardPrebranchedFallthrough(llvm::BasicBlock *Exit,
596 llvm::BasicBlock *From,
597 llvm::BasicBlock *To) {
598 // Exit is the exit block of a cleanup, so it always terminates in
599 // an unconditional branch or a switch.
600 llvm::Instruction *Term = Exit->getTerminator();
602 if (llvm::BranchInst *Br = dyn_cast<llvm::BranchInst>(Term)) {
603 assert(Br->isUnconditional() && Br->getSuccessor(0) == From);
604 Br->setSuccessor(0, To);
605 } else {
606 llvm::SwitchInst *Switch = cast<llvm::SwitchInst>(Term);
607 for (unsigned I = 0, E = Switch->getNumSuccessors(); I != E; ++I)
608 if (Switch->getSuccessor(I) == From)
609 Switch->setSuccessor(I, To);
613 /// We don't need a normal entry block for the given cleanup.
614 /// Optimistic fixup branches can cause these blocks to come into
615 /// existence anyway; if so, destroy it.
617 /// The validity of this transformation is very much specific to the
618 /// exact ways in which we form branches to cleanup entries.
619 static void destroyOptimisticNormalEntry(CodeGenFunction &CGF,
620 EHCleanupScope &scope) {
621 llvm::BasicBlock *entry = scope.getNormalBlock();
622 if (!entry) return;
624 // Replace all the uses with unreachable.
625 llvm::BasicBlock *unreachableBB = CGF.getUnreachableBlock();
626 for (llvm::BasicBlock::use_iterator
627 i = entry->use_begin(), e = entry->use_end(); i != e; ) {
628 llvm::Use &use = *i;
629 ++i;
631 use.set(unreachableBB);
633 // The only uses should be fixup switches.
634 llvm::SwitchInst *si = cast<llvm::SwitchInst>(use.getUser());
635 if (si->getNumCases() == 1 && si->getDefaultDest() == unreachableBB) {
636 // Replace the switch with a branch.
637 llvm::BranchInst::Create(si->case_begin()->getCaseSuccessor(), si);
639 // The switch operand is a load from the cleanup-dest alloca.
640 llvm::LoadInst *condition = cast<llvm::LoadInst>(si->getCondition());
642 // Destroy the switch.
643 si->eraseFromParent();
645 // Destroy the load.
646 assert(condition->getOperand(0) == CGF.NormalCleanupDest.getPointer());
647 assert(condition->use_empty());
648 condition->eraseFromParent();
652 assert(entry->use_empty());
653 delete entry;
656 /// Pops a cleanup block. If the block includes a normal cleanup, the
657 /// current insertion point is threaded through the cleanup, as are
658 /// any branch fixups on the cleanup.
659 void CodeGenFunction::PopCleanupBlock(bool FallthroughIsBranchThrough) {
660 assert(!EHStack.empty() && "cleanup stack is empty!");
661 assert(isa<EHCleanupScope>(*EHStack.begin()) && "top not a cleanup!");
662 EHCleanupScope &Scope = cast<EHCleanupScope>(*EHStack.begin());
663 assert(Scope.getFixupDepth() <= EHStack.getNumBranchFixups());
665 // Remember activation information.
666 bool IsActive = Scope.isActive();
667 Address NormalActiveFlag =
668 Scope.shouldTestFlagInNormalCleanup() ? Scope.getActiveFlag()
669 : Address::invalid();
670 Address EHActiveFlag =
671 Scope.shouldTestFlagInEHCleanup() ? Scope.getActiveFlag()
672 : Address::invalid();
674 // Check whether we need an EH cleanup. This is only true if we've
675 // generated a lazy EH cleanup block.
676 llvm::BasicBlock *EHEntry = Scope.getCachedEHDispatchBlock();
677 assert(Scope.hasEHBranches() == (EHEntry != nullptr));
678 bool RequiresEHCleanup = (EHEntry != nullptr);
679 EHScopeStack::stable_iterator EHParent = Scope.getEnclosingEHScope();
681 // Check the three conditions which might require a normal cleanup:
683 // - whether there are branch fix-ups through this cleanup
684 unsigned FixupDepth = Scope.getFixupDepth();
685 bool HasFixups = EHStack.getNumBranchFixups() != FixupDepth;
687 // - whether there are branch-throughs or branch-afters
688 bool HasExistingBranches = Scope.hasBranches();
690 // - whether there's a fallthrough
691 llvm::BasicBlock *FallthroughSource = Builder.GetInsertBlock();
692 bool HasFallthrough = (FallthroughSource != nullptr && IsActive);
694 // Branch-through fall-throughs leave the insertion point set to the
695 // end of the last cleanup, which points to the current scope. The
696 // rest of IR gen doesn't need to worry about this; it only happens
697 // during the execution of PopCleanupBlocks().
698 bool HasPrebranchedFallthrough =
699 (FallthroughSource && FallthroughSource->getTerminator());
701 // If this is a normal cleanup, then having a prebranched
702 // fallthrough implies that the fallthrough source unconditionally
703 // jumps here.
704 assert(!Scope.isNormalCleanup() || !HasPrebranchedFallthrough ||
705 (Scope.getNormalBlock() &&
706 FallthroughSource->getTerminator()->getSuccessor(0)
707 == Scope.getNormalBlock()));
709 bool RequiresNormalCleanup = false;
710 if (Scope.isNormalCleanup() &&
711 (HasFixups || HasExistingBranches || HasFallthrough)) {
712 RequiresNormalCleanup = true;
715 // If we have a prebranched fallthrough into an inactive normal
716 // cleanup, rewrite it so that it leads to the appropriate place.
717 if (Scope.isNormalCleanup() && HasPrebranchedFallthrough && !IsActive) {
718 llvm::BasicBlock *prebranchDest;
720 // If the prebranch is semantically branching through the next
721 // cleanup, just forward it to the next block, leaving the
722 // insertion point in the prebranched block.
723 if (FallthroughIsBranchThrough) {
724 EHScope &enclosing = *EHStack.find(Scope.getEnclosingNormalCleanup());
725 prebranchDest = CreateNormalEntry(*this, cast<EHCleanupScope>(enclosing));
727 // Otherwise, we need to make a new block. If the normal cleanup
728 // isn't being used at all, we could actually reuse the normal
729 // entry block, but this is simpler, and it avoids conflicts with
730 // dead optimistic fixup branches.
731 } else {
732 prebranchDest = createBasicBlock("forwarded-prebranch");
733 EmitBlock(prebranchDest);
736 llvm::BasicBlock *normalEntry = Scope.getNormalBlock();
737 assert(normalEntry && !normalEntry->use_empty());
739 ForwardPrebranchedFallthrough(FallthroughSource,
740 normalEntry, prebranchDest);
743 // If we don't need the cleanup at all, we're done.
744 if (!RequiresNormalCleanup && !RequiresEHCleanup) {
745 destroyOptimisticNormalEntry(*this, Scope);
746 EHStack.popCleanup(); // safe because there are no fixups
747 assert(EHStack.getNumBranchFixups() == 0 ||
748 EHStack.hasNormalCleanups());
749 return;
752 // Copy the cleanup emission data out. This uses either a stack
753 // array or malloc'd memory, depending on the size, which is
754 // behavior that SmallVector would provide, if we could use it
755 // here. Unfortunately, if you ask for a SmallVector<char>, the
756 // alignment isn't sufficient.
757 auto *CleanupSource = reinterpret_cast<char *>(Scope.getCleanupBuffer());
758 alignas(EHScopeStack::ScopeStackAlignment) char
759 CleanupBufferStack[8 * sizeof(void *)];
760 std::unique_ptr<char[]> CleanupBufferHeap;
761 size_t CleanupSize = Scope.getCleanupSize();
762 EHScopeStack::Cleanup *Fn;
764 if (CleanupSize <= sizeof(CleanupBufferStack)) {
765 memcpy(CleanupBufferStack, CleanupSource, CleanupSize);
766 Fn = reinterpret_cast<EHScopeStack::Cleanup *>(CleanupBufferStack);
767 } else {
768 CleanupBufferHeap.reset(new char[CleanupSize]);
769 memcpy(CleanupBufferHeap.get(), CleanupSource, CleanupSize);
770 Fn = reinterpret_cast<EHScopeStack::Cleanup *>(CleanupBufferHeap.get());
773 EHScopeStack::Cleanup::Flags cleanupFlags;
774 if (Scope.isNormalCleanup())
775 cleanupFlags.setIsNormalCleanupKind();
776 if (Scope.isEHCleanup())
777 cleanupFlags.setIsEHCleanupKind();
779 // Under -EHa, invoke seh.scope.end() to mark scope end before dtor
780 bool IsEHa = getLangOpts().EHAsynch && !Scope.isLifetimeMarker();
781 const EHPersonality &Personality = EHPersonality::get(*this);
782 if (!RequiresNormalCleanup) {
783 // Mark CPP scope end for passed-by-value Arg temp
784 // per Windows ABI which is "normally" Cleanup in callee
785 if (IsEHa && getInvokeDest() && Builder.GetInsertBlock()) {
786 if (Personality.isMSVCXXPersonality())
787 EmitSehCppScopeEnd();
789 destroyOptimisticNormalEntry(*this, Scope);
790 EHStack.popCleanup();
791 } else {
792 // If we have a fallthrough and no other need for the cleanup,
793 // emit it directly.
794 if (HasFallthrough && !HasPrebranchedFallthrough && !HasFixups &&
795 !HasExistingBranches) {
797 // mark SEH scope end for fall-through flow
798 if (IsEHa && getInvokeDest()) {
799 if (Personality.isMSVCXXPersonality())
800 EmitSehCppScopeEnd();
801 else
802 EmitSehTryScopeEnd();
805 destroyOptimisticNormalEntry(*this, Scope);
806 EHStack.popCleanup();
808 EmitCleanup(*this, Fn, cleanupFlags, NormalActiveFlag);
810 // Otherwise, the best approach is to thread everything through
811 // the cleanup block and then try to clean up after ourselves.
812 } else {
813 // Force the entry block to exist.
814 llvm::BasicBlock *NormalEntry = CreateNormalEntry(*this, Scope);
816 // I. Set up the fallthrough edge in.
818 CGBuilderTy::InsertPoint savedInactiveFallthroughIP;
820 // If there's a fallthrough, we need to store the cleanup
821 // destination index. For fall-throughs this is always zero.
822 if (HasFallthrough) {
823 if (!HasPrebranchedFallthrough)
824 Builder.CreateStore(Builder.getInt32(0), getNormalCleanupDestSlot());
826 // Otherwise, save and clear the IP if we don't have fallthrough
827 // because the cleanup is inactive.
828 } else if (FallthroughSource) {
829 assert(!IsActive && "source without fallthrough for active cleanup");
830 savedInactiveFallthroughIP = Builder.saveAndClearIP();
833 // II. Emit the entry block. This implicitly branches to it if
834 // we have fallthrough. All the fixups and existing branches
835 // should already be branched to it.
836 EmitBlock(NormalEntry);
838 // intercept normal cleanup to mark SEH scope end
839 if (IsEHa && getInvokeDest()) {
840 if (Personality.isMSVCXXPersonality())
841 EmitSehCppScopeEnd();
842 else
843 EmitSehTryScopeEnd();
846 // III. Figure out where we're going and build the cleanup
847 // epilogue.
849 bool HasEnclosingCleanups =
850 (Scope.getEnclosingNormalCleanup() != EHStack.stable_end());
852 // Compute the branch-through dest if we need it:
853 // - if there are branch-throughs threaded through the scope
854 // - if fall-through is a branch-through
855 // - if there are fixups that will be optimistically forwarded
856 // to the enclosing cleanup
857 llvm::BasicBlock *BranchThroughDest = nullptr;
858 if (Scope.hasBranchThroughs() ||
859 (FallthroughSource && FallthroughIsBranchThrough) ||
860 (HasFixups && HasEnclosingCleanups)) {
861 assert(HasEnclosingCleanups);
862 EHScope &S = *EHStack.find(Scope.getEnclosingNormalCleanup());
863 BranchThroughDest = CreateNormalEntry(*this, cast<EHCleanupScope>(S));
866 llvm::BasicBlock *FallthroughDest = nullptr;
867 SmallVector<llvm::Instruction*, 2> InstsToAppend;
869 // If there's exactly one branch-after and no other threads,
870 // we can route it without a switch.
871 if (!Scope.hasBranchThroughs() && !HasFixups && !HasFallthrough &&
872 Scope.getNumBranchAfters() == 1) {
873 assert(!BranchThroughDest || !IsActive);
875 // Clean up the possibly dead store to the cleanup dest slot.
876 llvm::Instruction *NormalCleanupDestSlot =
877 cast<llvm::Instruction>(getNormalCleanupDestSlot().getPointer());
878 if (NormalCleanupDestSlot->hasOneUse()) {
879 NormalCleanupDestSlot->user_back()->eraseFromParent();
880 NormalCleanupDestSlot->eraseFromParent();
881 NormalCleanupDest = Address::invalid();
884 llvm::BasicBlock *BranchAfter = Scope.getBranchAfterBlock(0);
885 InstsToAppend.push_back(llvm::BranchInst::Create(BranchAfter));
887 // Build a switch-out if we need it:
888 // - if there are branch-afters threaded through the scope
889 // - if fall-through is a branch-after
890 // - if there are fixups that have nowhere left to go and
891 // so must be immediately resolved
892 } else if (Scope.getNumBranchAfters() ||
893 (HasFallthrough && !FallthroughIsBranchThrough) ||
894 (HasFixups && !HasEnclosingCleanups)) {
896 llvm::BasicBlock *Default =
897 (BranchThroughDest ? BranchThroughDest : getUnreachableBlock());
899 // TODO: base this on the number of branch-afters and fixups
900 const unsigned SwitchCapacity = 10;
902 // pass the abnormal exit flag to Fn (SEH cleanup)
903 cleanupFlags.setHasExitSwitch();
905 llvm::LoadInst *Load =
906 createLoadInstBefore(getNormalCleanupDestSlot(), "cleanup.dest",
907 nullptr);
908 llvm::SwitchInst *Switch =
909 llvm::SwitchInst::Create(Load, Default, SwitchCapacity);
911 InstsToAppend.push_back(Load);
912 InstsToAppend.push_back(Switch);
914 // Branch-after fallthrough.
915 if (FallthroughSource && !FallthroughIsBranchThrough) {
916 FallthroughDest = createBasicBlock("cleanup.cont");
917 if (HasFallthrough)
918 Switch->addCase(Builder.getInt32(0), FallthroughDest);
921 for (unsigned I = 0, E = Scope.getNumBranchAfters(); I != E; ++I) {
922 Switch->addCase(Scope.getBranchAfterIndex(I),
923 Scope.getBranchAfterBlock(I));
926 // If there aren't any enclosing cleanups, we can resolve all
927 // the fixups now.
928 if (HasFixups && !HasEnclosingCleanups)
929 ResolveAllBranchFixups(*this, Switch, NormalEntry);
930 } else {
931 // We should always have a branch-through destination in this case.
932 assert(BranchThroughDest);
933 InstsToAppend.push_back(llvm::BranchInst::Create(BranchThroughDest));
936 // IV. Pop the cleanup and emit it.
937 EHStack.popCleanup();
938 assert(EHStack.hasNormalCleanups() == HasEnclosingCleanups);
940 EmitCleanup(*this, Fn, cleanupFlags, NormalActiveFlag);
942 // Append the prepared cleanup prologue from above.
943 llvm::BasicBlock *NormalExit = Builder.GetInsertBlock();
944 for (unsigned I = 0, E = InstsToAppend.size(); I != E; ++I)
945 InstsToAppend[I]->insertInto(NormalExit, NormalExit->end());
947 // Optimistically hope that any fixups will continue falling through.
948 for (unsigned I = FixupDepth, E = EHStack.getNumBranchFixups();
949 I < E; ++I) {
950 BranchFixup &Fixup = EHStack.getBranchFixup(I);
951 if (!Fixup.Destination) continue;
952 if (!Fixup.OptimisticBranchBlock) {
953 createStoreInstBefore(Builder.getInt32(Fixup.DestinationIndex),
954 getNormalCleanupDestSlot(),
955 Fixup.InitialBranch);
956 Fixup.InitialBranch->setSuccessor(0, NormalEntry);
958 Fixup.OptimisticBranchBlock = NormalExit;
961 // V. Set up the fallthrough edge out.
963 // Case 1: a fallthrough source exists but doesn't branch to the
964 // cleanup because the cleanup is inactive.
965 if (!HasFallthrough && FallthroughSource) {
966 // Prebranched fallthrough was forwarded earlier.
967 // Non-prebranched fallthrough doesn't need to be forwarded.
968 // Either way, all we need to do is restore the IP we cleared before.
969 assert(!IsActive);
970 Builder.restoreIP(savedInactiveFallthroughIP);
972 // Case 2: a fallthrough source exists and should branch to the
973 // cleanup, but we're not supposed to branch through to the next
974 // cleanup.
975 } else if (HasFallthrough && FallthroughDest) {
976 assert(!FallthroughIsBranchThrough);
977 EmitBlock(FallthroughDest);
979 // Case 3: a fallthrough source exists and should branch to the
980 // cleanup and then through to the next.
981 } else if (HasFallthrough) {
982 // Everything is already set up for this.
984 // Case 4: no fallthrough source exists.
985 } else {
986 Builder.ClearInsertionPoint();
989 // VI. Assorted cleaning.
991 // Check whether we can merge NormalEntry into a single predecessor.
992 // This might invalidate (non-IR) pointers to NormalEntry.
993 llvm::BasicBlock *NewNormalEntry =
994 SimplifyCleanupEntry(*this, NormalEntry);
996 // If it did invalidate those pointers, and NormalEntry was the same
997 // as NormalExit, go back and patch up the fixups.
998 if (NewNormalEntry != NormalEntry && NormalEntry == NormalExit)
999 for (unsigned I = FixupDepth, E = EHStack.getNumBranchFixups();
1000 I < E; ++I)
1001 EHStack.getBranchFixup(I).OptimisticBranchBlock = NewNormalEntry;
1005 assert(EHStack.hasNormalCleanups() || EHStack.getNumBranchFixups() == 0);
1007 // Emit the EH cleanup if required.
1008 if (RequiresEHCleanup) {
1009 CGBuilderTy::InsertPoint SavedIP = Builder.saveAndClearIP();
1011 EmitBlock(EHEntry);
1013 llvm::BasicBlock *NextAction = getEHDispatchBlock(EHParent);
1015 // Push a terminate scope or cleanupendpad scope around the potentially
1016 // throwing cleanups. For funclet EH personalities, the cleanupendpad models
1017 // program termination when cleanups throw.
1018 bool PushedTerminate = false;
1019 SaveAndRestore RestoreCurrentFuncletPad(CurrentFuncletPad);
1020 llvm::CleanupPadInst *CPI = nullptr;
1022 const EHPersonality &Personality = EHPersonality::get(*this);
1023 if (Personality.usesFuncletPads()) {
1024 llvm::Value *ParentPad = CurrentFuncletPad;
1025 if (!ParentPad)
1026 ParentPad = llvm::ConstantTokenNone::get(CGM.getLLVMContext());
1027 CurrentFuncletPad = CPI = Builder.CreateCleanupPad(ParentPad);
1030 // Non-MSVC personalities need to terminate when an EH cleanup throws.
1031 if (!Personality.isMSVCPersonality()) {
1032 EHStack.pushTerminate();
1033 PushedTerminate = true;
1034 } else if (IsEHa && getInvokeDest()) {
1035 EmitSehCppScopeEnd();
1038 // We only actually emit the cleanup code if the cleanup is either
1039 // active or was used before it was deactivated.
1040 if (EHActiveFlag.isValid() || IsActive) {
1041 cleanupFlags.setIsForEHCleanup();
1042 EmitCleanup(*this, Fn, cleanupFlags, EHActiveFlag);
1045 if (CPI)
1046 Builder.CreateCleanupRet(CPI, NextAction);
1047 else
1048 Builder.CreateBr(NextAction);
1050 // Leave the terminate scope.
1051 if (PushedTerminate)
1052 EHStack.popTerminate();
1054 Builder.restoreIP(SavedIP);
1056 SimplifyCleanupEntry(*this, EHEntry);
1060 /// isObviouslyBranchWithoutCleanups - Return true if a branch to the
1061 /// specified destination obviously has no cleanups to run. 'false' is always
1062 /// a conservatively correct answer for this method.
1063 bool CodeGenFunction::isObviouslyBranchWithoutCleanups(JumpDest Dest) const {
1064 assert(Dest.getScopeDepth().encloses(EHStack.stable_begin())
1065 && "stale jump destination");
1067 // Calculate the innermost active normal cleanup.
1068 EHScopeStack::stable_iterator TopCleanup =
1069 EHStack.getInnermostActiveNormalCleanup();
1071 // If we're not in an active normal cleanup scope, or if the
1072 // destination scope is within the innermost active normal cleanup
1073 // scope, we don't need to worry about fixups.
1074 if (TopCleanup == EHStack.stable_end() ||
1075 TopCleanup.encloses(Dest.getScopeDepth())) // works for invalid
1076 return true;
1078 // Otherwise, we might need some cleanups.
1079 return false;
1083 /// Terminate the current block by emitting a branch which might leave
1084 /// the current cleanup-protected scope. The target scope may not yet
1085 /// be known, in which case this will require a fixup.
1087 /// As a side-effect, this method clears the insertion point.
1088 void CodeGenFunction::EmitBranchThroughCleanup(JumpDest Dest) {
1089 assert(Dest.getScopeDepth().encloses(EHStack.stable_begin())
1090 && "stale jump destination");
1092 if (!HaveInsertPoint())
1093 return;
1095 // Create the branch.
1096 llvm::BranchInst *BI = Builder.CreateBr(Dest.getBlock());
1098 // Calculate the innermost active normal cleanup.
1099 EHScopeStack::stable_iterator
1100 TopCleanup = EHStack.getInnermostActiveNormalCleanup();
1102 // If we're not in an active normal cleanup scope, or if the
1103 // destination scope is within the innermost active normal cleanup
1104 // scope, we don't need to worry about fixups.
1105 if (TopCleanup == EHStack.stable_end() ||
1106 TopCleanup.encloses(Dest.getScopeDepth())) { // works for invalid
1107 Builder.ClearInsertionPoint();
1108 return;
1111 // If we can't resolve the destination cleanup scope, just add this
1112 // to the current cleanup scope as a branch fixup.
1113 if (!Dest.getScopeDepth().isValid()) {
1114 BranchFixup &Fixup = EHStack.addBranchFixup();
1115 Fixup.Destination = Dest.getBlock();
1116 Fixup.DestinationIndex = Dest.getDestIndex();
1117 Fixup.InitialBranch = BI;
1118 Fixup.OptimisticBranchBlock = nullptr;
1120 Builder.ClearInsertionPoint();
1121 return;
1124 // Otherwise, thread through all the normal cleanups in scope.
1126 // Store the index at the start.
1127 llvm::ConstantInt *Index = Builder.getInt32(Dest.getDestIndex());
1128 createStoreInstBefore(Index, getNormalCleanupDestSlot(), BI);
1130 // Adjust BI to point to the first cleanup block.
1132 EHCleanupScope &Scope =
1133 cast<EHCleanupScope>(*EHStack.find(TopCleanup));
1134 BI->setSuccessor(0, CreateNormalEntry(*this, Scope));
1137 // Add this destination to all the scopes involved.
1138 EHScopeStack::stable_iterator I = TopCleanup;
1139 EHScopeStack::stable_iterator E = Dest.getScopeDepth();
1140 if (E.strictlyEncloses(I)) {
1141 while (true) {
1142 EHCleanupScope &Scope = cast<EHCleanupScope>(*EHStack.find(I));
1143 assert(Scope.isNormalCleanup());
1144 I = Scope.getEnclosingNormalCleanup();
1146 // If this is the last cleanup we're propagating through, tell it
1147 // that there's a resolved jump moving through it.
1148 if (!E.strictlyEncloses(I)) {
1149 Scope.addBranchAfter(Index, Dest.getBlock());
1150 break;
1153 // Otherwise, tell the scope that there's a jump propagating
1154 // through it. If this isn't new information, all the rest of
1155 // the work has been done before.
1156 if (!Scope.addBranchThrough(Dest.getBlock()))
1157 break;
1161 Builder.ClearInsertionPoint();
1164 static bool IsUsedAsNormalCleanup(EHScopeStack &EHStack,
1165 EHScopeStack::stable_iterator C) {
1166 // If we needed a normal block for any reason, that counts.
1167 if (cast<EHCleanupScope>(*EHStack.find(C)).getNormalBlock())
1168 return true;
1170 // Check whether any enclosed cleanups were needed.
1171 for (EHScopeStack::stable_iterator
1172 I = EHStack.getInnermostNormalCleanup();
1173 I != C; ) {
1174 assert(C.strictlyEncloses(I));
1175 EHCleanupScope &S = cast<EHCleanupScope>(*EHStack.find(I));
1176 if (S.getNormalBlock()) return true;
1177 I = S.getEnclosingNormalCleanup();
1180 return false;
1183 static bool IsUsedAsEHCleanup(EHScopeStack &EHStack,
1184 EHScopeStack::stable_iterator cleanup) {
1185 // If we needed an EH block for any reason, that counts.
1186 if (EHStack.find(cleanup)->hasEHBranches())
1187 return true;
1189 // Check whether any enclosed cleanups were needed.
1190 for (EHScopeStack::stable_iterator
1191 i = EHStack.getInnermostEHScope(); i != cleanup; ) {
1192 assert(cleanup.strictlyEncloses(i));
1194 EHScope &scope = *EHStack.find(i);
1195 if (scope.hasEHBranches())
1196 return true;
1198 i = scope.getEnclosingEHScope();
1201 return false;
1204 enum ForActivation_t {
1205 ForActivation,
1206 ForDeactivation
1209 /// The given cleanup block is changing activation state. Configure a
1210 /// cleanup variable if necessary.
1212 /// It would be good if we had some way of determining if there were
1213 /// extra uses *after* the change-over point.
1214 static void SetupCleanupBlockActivation(CodeGenFunction &CGF,
1215 EHScopeStack::stable_iterator C,
1216 ForActivation_t kind,
1217 llvm::Instruction *dominatingIP) {
1218 EHCleanupScope &Scope = cast<EHCleanupScope>(*CGF.EHStack.find(C));
1220 // We always need the flag if we're activating the cleanup in a
1221 // conditional context, because we have to assume that the current
1222 // location doesn't necessarily dominate the cleanup's code.
1223 bool isActivatedInConditional =
1224 (kind == ForActivation && CGF.isInConditionalBranch());
1226 bool needFlag = false;
1228 // Calculate whether the cleanup was used:
1230 // - as a normal cleanup
1231 if (Scope.isNormalCleanup() &&
1232 (isActivatedInConditional || IsUsedAsNormalCleanup(CGF.EHStack, C))) {
1233 Scope.setTestFlagInNormalCleanup();
1234 needFlag = true;
1237 // - as an EH cleanup
1238 if (Scope.isEHCleanup() &&
1239 (isActivatedInConditional || IsUsedAsEHCleanup(CGF.EHStack, C))) {
1240 Scope.setTestFlagInEHCleanup();
1241 needFlag = true;
1244 // If it hasn't yet been used as either, we're done.
1245 if (!needFlag) return;
1247 Address var = Scope.getActiveFlag();
1248 if (!var.isValid()) {
1249 var = CGF.CreateTempAlloca(CGF.Builder.getInt1Ty(), CharUnits::One(),
1250 "cleanup.isactive");
1251 Scope.setActiveFlag(var);
1253 assert(dominatingIP && "no existing variable and no dominating IP!");
1255 // Initialize to true or false depending on whether it was
1256 // active up to this point.
1257 llvm::Constant *value = CGF.Builder.getInt1(kind == ForDeactivation);
1259 // If we're in a conditional block, ignore the dominating IP and
1260 // use the outermost conditional branch.
1261 if (CGF.isInConditionalBranch()) {
1262 CGF.setBeforeOutermostConditional(value, var);
1263 } else {
1264 createStoreInstBefore(value, var, dominatingIP);
1268 CGF.Builder.CreateStore(CGF.Builder.getInt1(kind == ForActivation), var);
1271 /// Activate a cleanup that was created in an inactivated state.
1272 void CodeGenFunction::ActivateCleanupBlock(EHScopeStack::stable_iterator C,
1273 llvm::Instruction *dominatingIP) {
1274 assert(C != EHStack.stable_end() && "activating bottom of stack?");
1275 EHCleanupScope &Scope = cast<EHCleanupScope>(*EHStack.find(C));
1276 assert(!Scope.isActive() && "double activation");
1278 SetupCleanupBlockActivation(*this, C, ForActivation, dominatingIP);
1280 Scope.setActive(true);
1283 /// Deactive a cleanup that was created in an active state.
1284 void CodeGenFunction::DeactivateCleanupBlock(EHScopeStack::stable_iterator C,
1285 llvm::Instruction *dominatingIP) {
1286 assert(C != EHStack.stable_end() && "deactivating bottom of stack?");
1287 EHCleanupScope &Scope = cast<EHCleanupScope>(*EHStack.find(C));
1288 assert(Scope.isActive() && "double deactivation");
1290 // If it's the top of the stack, just pop it, but do so only if it belongs
1291 // to the current RunCleanupsScope.
1292 if (C == EHStack.stable_begin() &&
1293 CurrentCleanupScopeDepth.strictlyEncloses(C)) {
1294 // Per comment below, checking EHAsynch is not really necessary
1295 // it's there to assure zero-impact w/o EHAsynch option
1296 if (!Scope.isNormalCleanup() && getLangOpts().EHAsynch) {
1297 PopCleanupBlock();
1298 } else {
1299 // If it's a normal cleanup, we need to pretend that the
1300 // fallthrough is unreachable.
1301 CGBuilderTy::InsertPoint SavedIP = Builder.saveAndClearIP();
1302 PopCleanupBlock();
1303 Builder.restoreIP(SavedIP);
1305 return;
1308 // Otherwise, follow the general case.
1309 SetupCleanupBlockActivation(*this, C, ForDeactivation, dominatingIP);
1311 Scope.setActive(false);
1314 Address CodeGenFunction::getNormalCleanupDestSlot() {
1315 if (!NormalCleanupDest.isValid())
1316 NormalCleanupDest =
1317 CreateDefaultAlignTempAlloca(Builder.getInt32Ty(), "cleanup.dest.slot");
1318 return NormalCleanupDest;
1321 /// Emits all the code to cause the given temporary to be cleaned up.
1322 void CodeGenFunction::EmitCXXTemporary(const CXXTemporary *Temporary,
1323 QualType TempType,
1324 Address Ptr) {
1325 pushDestroy(NormalAndEHCleanup, Ptr, TempType, destroyCXXObject,
1326 /*useEHCleanup*/ true);
1329 // Need to set "funclet" in OperandBundle properly for noThrow
1330 // intrinsic (see CGCall.cpp)
1331 static void EmitSehScope(CodeGenFunction &CGF,
1332 llvm::FunctionCallee &SehCppScope) {
1333 llvm::BasicBlock *InvokeDest = CGF.getInvokeDest();
1334 assert(CGF.Builder.GetInsertBlock() && InvokeDest);
1335 llvm::BasicBlock *Cont = CGF.createBasicBlock("invoke.cont");
1336 SmallVector<llvm::OperandBundleDef, 1> BundleList =
1337 CGF.getBundlesForFunclet(SehCppScope.getCallee());
1338 if (CGF.CurrentFuncletPad)
1339 BundleList.emplace_back("funclet", CGF.CurrentFuncletPad);
1340 CGF.Builder.CreateInvoke(SehCppScope, Cont, InvokeDest, std::nullopt,
1341 BundleList);
1342 CGF.EmitBlock(Cont);
1345 // Invoke a llvm.seh.scope.begin at the beginning of a CPP scope for -EHa
1346 void CodeGenFunction::EmitSehCppScopeBegin() {
1347 assert(getLangOpts().EHAsynch);
1348 llvm::FunctionType *FTy =
1349 llvm::FunctionType::get(CGM.VoidTy, /*isVarArg=*/false);
1350 llvm::FunctionCallee SehCppScope =
1351 CGM.CreateRuntimeFunction(FTy, "llvm.seh.scope.begin");
1352 EmitSehScope(*this, SehCppScope);
1355 // Invoke a llvm.seh.scope.end at the end of a CPP scope for -EHa
1356 // llvm.seh.scope.end is emitted before popCleanup, so it's "invoked"
1357 void CodeGenFunction::EmitSehCppScopeEnd() {
1358 assert(getLangOpts().EHAsynch);
1359 llvm::FunctionType *FTy =
1360 llvm::FunctionType::get(CGM.VoidTy, /*isVarArg=*/false);
1361 llvm::FunctionCallee SehCppScope =
1362 CGM.CreateRuntimeFunction(FTy, "llvm.seh.scope.end");
1363 EmitSehScope(*this, SehCppScope);
1366 // Invoke a llvm.seh.try.begin at the beginning of a SEH scope for -EHa
1367 void CodeGenFunction::EmitSehTryScopeBegin() {
1368 assert(getLangOpts().EHAsynch);
1369 llvm::FunctionType *FTy =
1370 llvm::FunctionType::get(CGM.VoidTy, /*isVarArg=*/false);
1371 llvm::FunctionCallee SehCppScope =
1372 CGM.CreateRuntimeFunction(FTy, "llvm.seh.try.begin");
1373 EmitSehScope(*this, SehCppScope);
1376 // Invoke a llvm.seh.try.end at the end of a SEH scope for -EHa
1377 void CodeGenFunction::EmitSehTryScopeEnd() {
1378 assert(getLangOpts().EHAsynch);
1379 llvm::FunctionType *FTy =
1380 llvm::FunctionType::get(CGM.VoidTy, /*isVarArg=*/false);
1381 llvm::FunctionCallee SehCppScope =
1382 CGM.CreateRuntimeFunction(FTy, "llvm.seh.try.end");
1383 EmitSehScope(*this, SehCppScope);